Screen sharing among computing devices such as computers, is an important tool for people at different locations to share information and achieve various tasks. For example, if a problem arises on a remote computing device, a technician at a viewing device may be able to address the problem by signing onto a computer and viewing the Graphical User Interface (GUI) of the remote computing device with the problem. This eliminates the need for the technician to travel to the problem site. Screen sharing also allows workers to access their work computers from any Internet-enabled device, including home computers, laptops and even PDAs. Another advantage of screen sharing is presentation sharing, which turns dry teleconferences into engaging online presentations.
In order to share screen content, the screen content displayed on a monitor need to be collected and transmitted to a remote computing device. Conventionally, the local computing device samples pixel data of a screen image at a certain rate, for example, 20 frame per second. The sampled pixel data of the screen image then is compressed, packaged and transmitted to the remote computing device. The remote computing decompresses the received data, and displays it on its monitor. Alternatively, in order to reduce network resource consumption, instead of transmitting a whole screen image, the local computing device may compare a screen image to be displayed with a previous screen display, and only sends updates to the previous screen image to the remote computing device.
The conventional way of screen sharing works acceptably when the screen content includes only static images. It produces unsatisfactory results, however, when the screen content includes video images. When the remote computing device reproduces the shared screen based on the captured screen pixel data sent by the sharing device, the quality of the video images in the reproduced screen can be significantly degraded.